1. Field of the Invention
The invention relates to a method and a device for inactivating a microbiologically contaminated mass containing solid particles with accelerated electrons.
2. Discussion of Background Information
Microbiologically contaminated products or waste occur primarily in the pharmaceutical and biotechnological industry, in the course of animal testing, in the disposal of animal carcasses, in waste processing and waste water treatment and in animal production in the form of dung, to name only a few examples.
Biologically contaminated liquid or solid waste is assigned to different biosafety classes. Previously, waste of this type has been inactivated chiefly chemically or thermally, that is, the microbiological contamination in the form of viruses, bacteria, microfungi and possibly prions is eliminated.
It should be understood below under the term “inactivate” that the harmful effect to health of microbiologically contaminated constituents of a mass is eliminated. This can mean on the one hand that the microbiologically contaminated constituents of a mass are sterilized. However, on the other hand it can also already be sufficient if the adhering microorganisms are influenced such that they are no longer capable of reproduction or that the number of microorganisms capable of reproduction is reduced in order to suppress their harmful effect to health.
The type of microbiologically contaminated waste ranges from aqueous liquids to hen's eggs from vaccine production to animal carcasses such as, for example, test mice. However, dung from animal husbandry is also often contaminated with bacteria such as, e.g. salmonella, which should be inactivated before being applied to the fields.
Depending on the type of waste and contamination (dangerousness of the viruses, bacteria, microfungi or prions), known methods for inactivation are associated with risks and in part with substantial disadvantages. In particular, for example, thermal methods require considerable energy expenditure, since temperatures above 70° C. or even above 130° C. and long exposure times are necessary.
Another method is the inactivation in the course of combustion. However, in this case the product is destroyed and is not available for any further use.
Chemical methods, such as, for example, the inactivation of waste from vaccine production (e.g., hatched hen's eggs) are often based on a treatment with acids or bases. This is associated with the risk that the inactivation of larger volumes does not cover every volume element. In addition, an inline monitoring of the process and a final validation are not possible. The guarantee of biosafety can therefore be carried out only through cyclical sampling. Furthermore, this method is associated with substantial waiting times, in order to ensure the necessary minimum exposure time of the acids or bases.
A major problem with the inactivation of microbiological contaminations is often associated with the fact that the products or waste contain solids such as bones, gristle, eggshells and the like. Conventional methods are effective in these solid constituents only to a limited extent, which entails further risks in the use, the detection and in the waste disposal.
It is known that germs or microorganisms can be destroyed by accelerated electrons. For example, in DE 199 42 142 A1, bulk seeds are acted on with accelerated electrons in freefall with multiple passes through, in order to destroy germs in the bulk seeds. DE 20 2006 015 636 U1 describes pourable plant products swirled in a chamber by a gas flow that are acted on with accelerated electrons. Both of these proposals are associated with the disadvantage that they are not suitable for germ reduction in masses that have liquid constituents.
Proposals are known from the field of water treatment in which germicidal liquids are acted on with accelerated electrons (WO 02/02466 A1, EP 0 931 765 A2, EP 0 024 487 A1). Again, devices and methods of this type are not suitable for the treatment of liquids that have microbiologically contaminated solid particles, because in these proposals there are no discernible measures that prevent the sedimentation of solid particles on the base of pipes or containers. In this way, the solids precipitated there are either not acted on at all with accelerated electrons or at least not from all sides, such that the entire mass of liquid and solid constituents is not inactivated.